Well, I have no idea what ratio 3rd gear would be on a 4-speed GTX, but I'd imagine it's geared for a bit below 250 mph :P Now 4th gear is going to be 1:00:1. Top speed is going to be determined mainly by the axle ratio. I'd imagine that about the hairiest axle ratio you could get by then would be around a 4.11:1. Put some fairly meaty 255/70/R15's on that sucker, which according to www.tirerack.com, turn about 720 revs per mile (also 720 rpm@ 60 mph, and that means your engine would be revving at about 2960 rpm @60. That engine would probably hit its peak hp around 4800 rpm, which would mean about 97 mph. And it would hit its redline of around 5500 rpm at around 111 mph.

Now on the flip side of that, I think you could special order a tall ratio axle of around 2.06:1. When you figure that's about half of a 4.11:1, that means you'd hit peak hp at a theoretical 194 mph, and top out at 222 mph! Of course, it doesn't take into account wind resistance, which is going to be fierce once you get up over 100 mph or so. And IIRC, for every doubling of speed, wind resistance is actually squared?

I'd say that with a moderate gear ratio, and in tip-top shape, that '72 GTX might, *might* top out at around 145-150 mph. IIRC, some of the fiercest police cars of all time were 1969 Polaras running 440's and 3.23:1 axles, and that's about what they'd top out at.

As for turning 3500 rpm@135 mph in 3rd gear? Well, doing the math, I'd take a wild guess and say that would be a 2.45:1 axle? And again, that's not taking into account aerodynamic drag. And I seriously doubt that anybody would put a 2.45:1 axle in a '72 GTX. And you sure as hell don't want to rev something like that up to 6500 rpm! There are many modern DOHC engines that redline around there...some big monster of a 440 that's better at pulling out stumps and flattening mountains isn't going to want to rev that fast without scattering parts for a wide, wide radius!

Maybe that '72 GTX came out of Canada, and had a metric speedo! I know a guy in one of my Mopar clubs with a '66 Fury that came from Canada, and it set up that way.

Here are some stats from Motor Trend and Car and Driver tests, circa 1971/1972, I'll let the reader decide what he wants to take from this info.These are merely speed/revs figures, not 1/4 mile times.

1971 440-6pk Road Runner, 4.10 rear 104 mph@5400 rpm

1971 383-4v Road Runner, 3.55 rear 98 mph@5000 rpm

1971 440-4v GTX, 3.23 rear 110 mph@4700 rpm

Interestingly enough, this '71 GTX did list a top speed of 130 mph @5500 rpm (redline).

Another article from Motor Trend compared three different 'Cudas, a 340 auto, 440-6 4-speed, and a Hemi auto. The 340 was the author's favorite, as the 440-6 was just too much of a chore to drive, its carb setup impossible to modulate between moderate acceleration and flat-out. The Hemi was easy to drive, also, just keep your foot out of it on takeoff. Top end on the cars (all at redline): 340 (4.10 rear)- 101 mph, 440-6 (3.54 rear)- 109 mph, 426 Hemi (3.55 rear)-112 mph.

Surmise what you will, but I drove some of these vehicles on a daily basis, and trust me, by 100 mph, they were mostly used up and acceleration was pretty slow thereafter. Here's a shocker- Car and Driver tested a Saturn Aura XR that was quicker and faster in the quarter than the '71 GTX! As far as I'm concerned, the golden age of cars is now.

Wow, those top speeds really are kinda sad, although I guess with those really quick axle ratios, they're just not going to get much of a top speed as they're really screaming by the time they hit 100.

I'm kinda surprised though, that the car with the 3.23:1 ratio only made it to 110. I figured a ratio like that would be a good enough "middle of the road" ratio to give good top speed without hurting acceleration too much.

Sad thing is, though, that I had an '89 Gran Fury ex police car, with a 318-4bbl and a 2.94 ratio. It would top out at about 120 mph, according to the Michigan State Police, at least. Heck, even my old '69 Dart GT, with a 225-1bbl and 2.76:1 axle could break 100 mph pretty easily. I was afraid to take it much higher than that, though. It actually felt like it had plenty of power left at that speed, but I have a feeling it wouldn't have gone much faster.

I use to work on the Gran Fury police cars,and would help calibrate the speedometer and would top out at 115,then we would flip over the air cleaner and get 120 out of them,it was a old trick we would do to get more speed and help the MPGs.I also worked on a '70 Fury police car with the 440,and it had 2:76 gears,I don't know what it top out at,but is was the fastest car I worked on ,the road test were awesome.I also had a '68 Road Runner with 3:23,and one time dragging a Vette I was doing 115 in third,shifted to forth and buried the speedo,the speedo only went to 120,so I don't know what the top end was,but is was fast.BTW the Vette beat me,but it wasn't stock.I would beat most stock vettes with the Runner.

I think you're right about the wind resistance factor, although I'd have to drag out the old physics texts to be sure.Really makes a difference when trying to get that last 10 mph, no doubt about it. And as you said, those big blocks with their 100 lb. cranks and 2 ft. strokes just don't like the top of the tach.

I use to work on the Gran Fury police cars,and would help calibrate the speedometer and would top out at 115,then we would flip over the air cleaner and get 120 out of them,it was a old trick we would do to get more speed and help the MPGs.

LOL, I do a similar trick with my '85 Silverado in the warmer spring/summer months. I have an old '68 Dodge Dart V-8 air cleaner top that I put on the Chevy. It has the tall 5" or so air filter, and the top part is actually too big to flip. But the Dart's air cleaner, which is flat, sits nicely on top of the air filter and exposes a great deal of it.

I don't know how much it REALLY helps acceleration on that dog, but it does seem to take off a bit quicker when trying to merge onto a highway, for instance. And it seems to improve fuel economy a bit, maybe .5-1.0 mpg. Which, when you're dealing with maybe 12-15 mpg to begin with, every little bit helps!

It does make it a bit crankier in cooler weather though, and I have a feeling that it screws with emissions.

During the winter,we had to flip the top back to normal.One reason was the engines would bog down because the air was to cold,plus fear of snow getting into the engine.Some emissions would be blocked off to gain power.Back then we didn't have emission testings.Plus we would take off the resonators to gain power.There were lots of tricks,thats why had the faster police cars.

Jeff Yerkovich, owner of R&A Motorsports, one of the country&#146;s leading restorer of Shelby Mustangs, CARSTAR in Riverside, Kan., re-created the &#147;Super Snake,&#148; a legendary experimental car produced by the Ford Motor Company in 1967. The prototype, never offered for production, featured Carroll Shelby-modified Mustang chassis, suspensions and bodies with big block motors delivering more than 400 horsepower. The renovated vehicle carries the Wimbleton white and blue stripe livery of the original vehicle and is authentic down to the paint drips and over-sprays on the chassis and undercarriages of the original cars.

The car is still awaiting Shelby certification and is currently on tour with CARSTAR making $$$ for the Make-A-Wish Foundation.

The Camaro is being built on the same platform used for the Holden Commodore/Pontiac G8, and the V8 version of that clocks in at just over 4,000 pounds. The Camaro will be shorter, but not enough to bring it under 3,700 (and probably not under 3,800 now that we have the G8 numbers).

The top speed at redline for a '70 Hemicuda with 3.54 gears is not 112@5000 rpm. The Hemis could rev to at least 6,000 rpm. 130 mph is more like it. Car & Driver got a '66 Hemi Satellite to 130 mph with the 426-Hemi and 3.54 gears.In the early '70s, Motor Trend listed under the specs that the speed in gears are limited by the length of the track and do not represent top speed.

This would also apply to the 340 'Cuda with 4.10 gears... 101 mph @ 5500 rpm, but the 340 could rev to 6000 rpm.And the 109 mph @ 5000 rpm for the 440-6 bbl 'Cuda meant that it should be able to reach 120 mph @ 5500 rpm.

I'd imagine those extra gears help out alot these days, too. Back in the day, they could gear a car for fast acceleration or a high top speed, but you always had to sacrifice one for the other. Back then you were usually stuck with a 3-speed automatic or 4-speed stick. Nowadays though, with all those extra transmission gears they can stick a really quick axle ratio in there for fast acceleration, but then throw on a really tall overdrive gear or two so that you don't redline so easily at higher speeds.

Back in the late 60's, they were able to get 440-powered Monaco and Polara copcars up to around 147 mph, with 3.23:1 gearing. Acceleration would suffer compared to those quicker ratios, but they were still no slouch off the line. Oh, and of course, the improved aerodynamics of today's cars helps out alot, too. Aerodynamics don't mean much from 0-60, but do come into play more in the quarter mile, and especially top speed.

I know about the 440 Police cars,I use to work on them,and I know they would do over 140.We had 2.76 gears posi.I had a 68 Road Runner 383 Magnum with 3.23 and I would bury my speedometer,but it only went to 120 so I never knew my top end.All I know is it was fast.I had the Hemi transmission with had nice gears in it,plus the Hemi clutch.

I was born before the era that the pony cars came out and got to watch them grow into more than just cars from the three big companys. The Camero Mustang, Cuda, cougar,challenger, dart, Comet have made the Muscle car era a part of history that we all can look back on with a smile and a tear. These cars will never be duplicated and I don't think that would the big three are trying to do now, They are trying to give you youngers a part of what we old guys have had for 44 years (19641/2 to 2008) bragging right over the imports of todays, and muscle heads of tomorrow.

Papasam and I are late to the party. If you checked old car mags, was the six pack option available in 72? I don't think so, but I'm not certain. I think the six pack and Hemi were discontinued after 71.What about them Challengers?

The 426 Hemi was dropped after 1971. However, Chrysler held onto some of its other high performance engines longer than most. You could still get a 440-6pack in a 1973 Charger. It put out 330 hp that year. That might sound tame compared to the glory days of the 60's, but remember that they rated hp differently starting in 1972, publishing net, rather than gross figures. 330 hp net would easily be 400-410 gross. To put it in perspective, the 426 Hemi, which was rated at 425 hp, was rated at 350 net.

For 1974, you could still get a Charger with a 280 hp 440. By that time though, I think it was a hot 4-bbl, rather than a 6-pack or dual quad.

As for the Challenger and Barracuda, they wussed out very quickly. In 1971 you could get a 440 6-pack or the Hemi. But for 1972, the top engine was a 245 hp 340 smallblock. It was actually a good performer, and would embarrass many big-blocks, but it wasn't not Hemi! For '73 they started phasing in a 360 which had about the same peak hp, but it had a narrower power band than the 340, so it didn't perform as well.

By 1974 though, I think everybody was out of the high-performance game. Olds, Buick, and Pontiac used to offer high-output versions of their 455's, but I think they were down to around 250 hp by 1974, and by 1975 you'd be lucky to see 200-210 hp out of a big-block. The Chevy 454 put out 270 hp back in 1972, but by '74 I think it got cut severely, and even worse by '75-76.

Chrysler did still have a 255 hp 440 in 1978, which was about as powerful as it got by that time. The only catch is, they were only offered in the midsize Monaco/Coronet police cars! They were pretty quick, too...fast enough that they'd even give most modern police cars a run for their money.

I guest I should ask just how many of you were actually driving does the first crisis, I was bron in 1952 and was just starting love the muscle car era when this crisis came along. I have heard all type of hear say crap about how and why it started with most of it being from some grand pop or grand mom that didn't even own a muscle car or even knew what they were. And yes the insurance was going up but that was nothing, new the car industry always lied about horse power in cars just to keep the insurance down and the insurance companies were just starting to change with the times. The mustang II was a nescessary car for the times along with nova,acclaim and a number of other car that were needed. If we are to talk these types of things aleast get all the facts.

Not just gas and insurance prices, but don't forget (excuse me while I channel my inner "Gore"), emission equipment choked the heck outta engines too. Unfortunately it was a necessary evil. I've lived in So. Cal all my life and I remember my eyes would burn from the smoggy air back then. Believe it or not, air quality here is much better than it was in the early 70's.

And yes the insurance was going up but that was nothing, new the car industry always lied about horse power in cars just to keep the insurance down and the insurance companies were just starting to change with the times.

I don't think high insurance rates played much of a part until the 1970's. If anything, most car companies were over-stating their hp in the 60's, rather than under-stating it. Horsepower is what sold cars in those days. Chrysler's 340 was one of the few under-rated engines...probably because if they listed its true horsepower, then people would question whether they really needed some of the bigger engines. It was rated around 270-275 hp with the 4-bbl. When the rating system went to net hp, it still had 245 hp, or about 89-90% of its gross rating. Many engines were lucky if their net rating was 70% of its gross rating, although to be fair, some engines had their compression cut at the same time, so there was a real loss in addition to the "paper" loss.